This section provides background information related to the present disclosure which is not necessarily prior art.
Electrical components, such as semiconductors, integrated circuit packages, transistors, etc., typically have pre-designed temperatures at which the electrical components optimally operate. Ideally, the pre-designed temperatures approximate the temperature of the surrounding air. But the operation of electrical components generates heat. If the heat is not removed, the electrical components may then operate at temperatures significantly higher than their normal or desirable operating temperature. Such excessive temperatures may adversely affect the operating characteristics of the electrical components and the operation of the associated device.
To avoid or at least reduce the adverse operating characteristics from the heat generation, the heat should be removed, for example, by conducting the heat from the operating electrical component to a heat sink. The heat sink may then be cooled by conventional convection and/or radiation techniques. During conduction, the heat may pass from the operating electrical component to the heat sink either by direct surface contact between the electrical component and heat sink and/or by contact of the electrical component and heat sink surfaces through an intermediate medium or thermal interface material. The thermal interface material may be used to fill the gap between thermal transfer surfaces, in order to increase thermal transfer efficiency as compared to having the gap filled with air, which is a relatively poor thermal conductor.
Heat spreaders are commonly used to spread the heat from one or more heat generating components such that the heat is not concentrated in a small area when transferred to a heat sink. An integrated heat spreader (IHS) is a type of heat spreader that may be used to spread the heat generated by operation of a central processing unit (CPU) or processor die. An integrated heat spreader or lid (e.g., a lid of an integrated circuit (IC) package, etc.) is typically a thermally-conductive metal (e.g., copper, etc.) plate that rests on top of the CPU or processor die.
Heat spreaders are also commonly used (e.g., as a lid, etc.) to protect chips or board-mounted electronic components often in conjunction with a sealed package. Accordingly, a heat spreader may also be referred to herein as a lid and vice versa.
A first thermal interface material or layer(s) (referred to as TIM1) may be used between an integrated heat spreader or lid and a heat source to reduce hot spots and generally reduce the temperature of the heat generating components or device. A second thermal interface material or layer(s) (referred to as TIM2) may be used between the lid or integrated heat spreader and the heat sink to increase thermal transfer efficiency from the heat spreader to the heat sink.
For example, FIG. 1 illustrates an exemplary electronic device 11 having a TIM1 or first thermal interface material 15. As shown in FIG. 1, the TIM1 or thermal interface material 15 is positioned between a heat spreader or lid 19 and a heat source 21, which may comprise one or more heat generating components or devices (e.g., a CPU, die within underfill, semiconductor device, flip chip device, graphics processing unit (GPU), digital signal processor (DSP), multiprocessor system, integrated circuit, multi-core processor, etc.), batteries, solar panels, etc. A TIM2 or second thermal interface material 25 is positioned between a heat sink 29 and the heat spreader or lid 19.
By way of example, the heat source 21 may comprise a central processing unit (CPU) or processor die mounted on a printed circuit board (PCB) 33. The PCB 33 may be made of FR4 (flame retardant fiberglass reinforced epoxy laminates) or other suitable material. Also in this example, the heat spreader or lid 19 is an integrated heat spreader (IHS), which may comprise metal or other thermally-conductive structure. The heat spreader or lid 19 includes a perimeter ridge, flange, or sidewall portions 37. Adhesive 41 is applied to and along the perimeter ridge 37 for attaching the heat spreader or lid 19 to the PCB 33. The perimeter ridge 37 may thus protrude sufficiently downward to extend around the silicon die on the PCB 33 and thereby allow contact between the adhesive 41 on the perimeter ridge 37 and the PCB 33. Advantageously, adhesively attaching the heat spreader or lid 19 to the PCB 33 may also help stiffen the package, which is attached to the base PCB. Also shown in FIG. 1 are pin connectors 45. The heat sink 29 may generally include a base from which outwardly protrude a series of fins.
As another example, an exemplary electronic device may include a thermal interface material positioned between a heat source and a heat sink without any intervening heat spreader between. In this example, the thermal interface material may thus be positioned directly between and/or against the heat sink and the heat source, which may comprise one or more heat generating components or devices (e.g., a CPU, die within underfill, semiconductor device, flip chip device, graphics processing unit (GPU), digital signal processor (DSP), multiprocessor system, integrated circuit, multi-core processor, etc.), batteries, solar panels, etc.